Speed control



July 7, 1970 A. N. PEALE 3,519,372

SPEED 1 CONTROL Filed Sept. 19, 1968 I? a 28 22 FIG.

3 -A s 7 F765 Q, N 4? JKQ FIG. 2 28 36 38 45 5% v 39 40 4.4 513 i f W4 INVENTOR ALFRED N. PEALE BY 47 IBM 4/ W H ATTORNEY United States Patent O 3,519,372 SPEED CONTROL Alfred N. Peale, Waverly, N.Y., assignor to Ingersoll- Rand Company, New York, N.Y., a corporation of New Jersey Filed Sept. 19, 1968, Ser. No. 760,882 Int. Cl. F01c 13/02, 21/16 U.S. Cl. 41843 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF INVENTION This invention relates to a device for stopping a fluid motor in the event of its unsafe overspeed. This invention is an improvement of the invention disclosed in the US. Pat. No. 2,897,832, issued on Aug. 4, 1959, to F. A. Jimerson.

The foregoing Jimerson patent used a lever to transmit mechanical motion between a valve and a governor mechanism. This lever was pivoted intermediate its ends like a see-saw and the governor mechanism contained a trip operative in response to overspeed to swing one of the arms of the lever aside from its operative position to allow the valve to close and disable the tool.

Due to the arrangement of having one of its arms swingable to one side, the lever had to be pivoted to a boss depending from the cap covering the tool motor. This arrangement resulted in the tool motor being disabled from operating when the cap was removed and, as a result, it was impossible to adjust the governor mechanism while the motor was operating.

SUMMARY OF INVENTION can be actuated by a centrifugal trip mechanism mounted on the governor. In this way, the governor mechanism is intact and operable with the motor cap removed whereby the governor mechanism can be adjusted with the motor operating.

BRIEF DESCRIPTION OF DRAWING The invention is described in connection with the accompanying drawing wherein:

FIG. 1 is an elevational view with portions being cut away of a portable power grinder incorporating the overspeed safety mechanism of this invention;

FIG. 2 is an enlarged fragmentary view of a portion of FIG. 1 with additional portions being cut away;

FIG. 3 is a fragmentary view similar to FIG. 2 and illustrating the overspeed mechanism after it has disabled the tool motor;

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FIG. 4 is a horizontal section taken on the line 44 in FIG. 3; and

FIG. 5 is an enlarged fragmentary horizontal section taken on the line 5-5 in FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENT The portable power grinder 1 shown in FIG. 1 includes a casing 2 carrying a handle 3 and containing an air motor 4 driving a shaft 5 carrying a grinding wheel 6. The grinding wheel 6 is partially surrounded by a safety guard 7. The casing 2 includes a removable cap or cover 8 enclosing the end of the motor 4 opposite the grinding wheel 6. The free end of the handle 3 includes a hose connection 9 adapted to be connected to an air hose (not shown) for driving the motor 4 and the handle further includes a thumb-operated throttle button 10 controlling the flow of compressed air to the motor 4.

After passing through the throttle 10, when it is open, the air supply flows through a passage 12 and into a vertically extending valve bore 13. A spool valve 14 is slidably mounted in the bore 13 and meters or controls air flowing from the valve bore 13 into an outlet port 15 which is connected to the inlet of the air motor 4. The spool valve 14 includes a vertical valve rod 16 which extends above and below the valve spool 14. The upper end of the valve rod 16 projects through the upper end of the valve bore 13, where it seals the end of the valve bore, and into the space 17 enclosed by the casing cap 8. A governor mechanism which will be described soon, moves this rod 16 up and down to cause the spool valve 14 to meter the air flow in accordance with the speed of the motor 4 to attempt to maintain the motor speed substantially uniform.

The lower end of the valve rod 16 carries a poppet valve 19 adapted to seat on and close the lower end of the valve bore 13 when the valve rod 16 is allowed to move upward to its full travel. A spring 20 urges the poppet valve 19 and valve rod 16 upwardly toward the closed position of the poppet valve 19. Normally, the governor mechanism, soon to be described, holds the poppet valve 19 open at all times. The only time that the poppet valve 19 should close is in the event of an overspeed of the motor, above a predetermined limit. All of the foregoing structure is conventional.

The governor mechanism includes a governor body 22 attached to the upper end of the motor shaft 5 and carrying a pair of diametrically located, pivoted, L-shaped flyweights 23 mounted to tilt radially outward under the influence of motor speed and to lift a governor stem 24. The governor stem 24 carries a ball bearing 25 having a central governor button 26.

The governor button 26 is interconnected to the top of the valve rod 16 by a see-saw type lever 28 pivoted intermediate its ends. The inner end of the lever 28 includes a downwardly curved tip 29 hearing on the governor button 26 and the outer end carries a threaded adjustment screw 30 adapted to engage the upper end of the valve rod 16. A spring 31 frictionally holds the adjustment screw 30 in its adjusted position.

As a result of the foregoing arrangement, an increase in speed of the motor will cause the governor button 26 to move upward, causing the outer end 30 of the lever 28 to tilt downward and to move the spool valve 14 downward to further restrict the outlet port 15. When the motor speed falls, the governor button 26 moves downward to allow the outer end of the lever 28 to tilt upward and the spool valve 14 to move up, thereby further opening the valve port 15. It is easily seen that this mechanism tends to control the motor speed to maintain it substantially uniform.

The invention in this application resides in the way that the governor lever 28 is pivoted and in a mechanism operative to release the pivot of the lever 28 whereby the poppet valve 19 can be automatically closed to stop the motor 4.

The lever 28 includes a downwardly projecting stem 33 located substantially in the middle of its length. A post 34 is fixed to the frame of the motor 4 and is bifurcated in its upper portion to form an upwardly opening notch flanked by a pair of post legs 37. The lever stem 33 slidably and pivotably rests in the notch and contains a pivot pin 35 having projecting ends slidably captured in slots 36 provided in the legs 37 of the post 34.

A sleeve 38 is rotatably mounted on the lower portion of the post 34 and includes a pair of circumferentially extending slots 39 surrounding the ends of a stop pin 40 fixed in the post 34. The stop pin 40 limits the rotation of the sleeve 38 to about ninety degrees as well as preventing it from sliding upwards on the post 34. The upper portion of the sleeve 38 is shaped to form a pair of bayonet shaped hooks 41 adapted to hook over the ends of the pivot pin 35 to hold the lever 28 in its normally pivoted position as shown in FIG. 2. The pivot pin 35 is released from the hooks 41 by rotating the sleeve 38 counterclockwise, as shown in FIG. 4, for about one quarter of a turn to the position shown in FIG. 3.

When the lever 28 is latched in its normally pivoted position as shown in FIG. 2, an overspeed trip mechanism is used to rotate the sleeve 38 to release the lever. A trip weight 43 is pivoted on the governor body 22 on the same pivoted as one of the flyweights 23. The trip weight 43 is urged inwardly by a tension spring 44 contained in a bore provided in the governor body 22 and attached at one end to an anchor pin 45. The strength of the spring 44 is selected to hold the trip weight against pivoting outwardly from the governor body 22 until and unless the speed of the motor rises above a predetermined safe speed. In the event that unsafe overspeed occurs, the trip weight 43 will swing radiaally outward to the position shown in FIGS. 3 and 4 and will strike a lug 47 integrally formed on the sleeve 38 to rotate the sleeve to a position wherein the hooks 41 release the pivot 35 and the lever 28, thereby allowing the poppet valve 19 to close and immediately stop the motor 4. When this takes place, the operator must remove the casing cap 8 to return the grinder to operating condition. At the same time, he can adjust the screw 30 to control the speed of the motor, while the tool is operating, to attempt to prevent further occurrences of motor overspeed.

One of the advantages of this invention is that the safety release mechanism is constructed in a manner so that the grinder motor can operate with the casing cap 8 removed whereby the governor speed can be more easily adjusted. Previous grinders of this type were constructed so that they could not operate with the cap 8 removed.

While only a single embodiment of the invention is illustrated and described in detail, this invention is not limited merely to this embodiment, but contemplates other embodiments and variations which utilize the concepts and teachings of this invention.

I claim:

1. A fluid-operated tool including an overspeed safety mechanism comprising:

a casing containing a rotary fluid motor;

a governor mechanism mounted on the shaft of said motor and movable axially in response to the speed of said motor;

a valve controlling the flow of fluid to said motor and including means normally urging it to a closed position;

a lever pivoted on an axis intermediate its ends and transmitting force between said governor mechanism and said valve, said lever, when in its normal pivoted position, being operative to prevent said valve from completely closing;

releasable pivot means holding said lever on its normal pivot axis and being releasable to disengage said lever whereby the lever is disabled and the valve automatically closes; and

means mounted on said motor to automatically release said pivot means in response to an undesirable overspeed of said motor.

2. The fluid-operated motor of claim 1 wherein:

said releasable pivot means is attached to a frame supporting the motor, projects outwardly from near one end of the motor and is located between the governor mechanism and the valve.

3. The fluid-operated motor of claim 2 wherein said releasable pivot means includes:

a post extending substantially parallel to the axis of the motor;

means slidably engaging said lever on said post; and

a rotatable sleeve on said post having a finger engaging and holding said lever in proper position on said post when in a first position on said post, and being rotatable to a second position wherein said finger releases said lever.

4. The fluid-operated motor of claim 3 wherein:

the outer end of said post includes a notch slidably holding said lever;

said lever includes a projecting pivot pin; and

said finger hooks over said pivot pin when said sleeve is in its first position to hold said lever in its pivoted position on said post.

5. The fluid-operated motor of claim 4 wherein:

said sleeve is rotatable to said second position by a trip which is pivoted on the governor mechanism and is operative to move radially outward in response to an unsafe overspeed of the motor to engage said sleeve and thereby rotate it to its second position.

References Cited UNITED STATES PATENTS EVERETTE A. POWELL, JR., Primary Examiner 

